the raw variable (Lynch & Walsh, 1998; Mather & Jinks, 1982). Previously, using the same Finnish twin sample, Dick, Pagan, et al. (2007) reported moderating effects of parental monitoring on adolescent smoking but not drinking. Our analyses differed from those of Dick, Pagan, et al. (2007) in that we used a semi-continuous measure of alcohol use frequency and assessed these findings using the bivariate moderation model and the newer extended univariate model. These differences potentially explain our findings of significant moderation of genetic influences with the raw variable but only a trend in the transformed variable.
